Donato Environmental Services ABN: 68083 254 015 Mobile: 0417 819 196 Int’l mobile: +61 417 819 196 Email: [email protected] Phone: +61 8 8842 1181 Fax +61 8 8842 1186 Influences of hypersaline tailings on wildlife cyanide toxicosis: Granny Smith Gold Mine Report to: Barrick Granny Smith Gold Mine 20 December 2010 FINAL REPORT Influences of hypersaline tailings on wildlife cyanide toxicosis: Granny Smith Gold Mine Disclaimer This report has been prepared and produced by Donato Environmental Services (ABN 68083 254 015) in good faith. However, Donato Environmental Services accepts no liability (including liability of negligence) and takes no responsibility for any loss that a user of this report or any third party may suffer or incur as a result of reliance or use, as stated or inferred in this report, and in particular for: • any errors, misinterpretations or omissions in the report; • any inaccuracy in the information and data on which this report is based or contained in this report; and • any interpretations, recommendations or opinions stated in, or which may be inferred from, this report. Citation Smith G.B., Donato, D.B., and Madden-Hallett, D., 2010, Influences of hypersaline tailings on wildlife cyanide toxicosis, Granny Smith Gold Mine, Draft Report, September, Donato Environmental Services, Darwin. Distribution Receivers Copies Date Issued Issued by Frances Mills, Leon Hill, Arlene Rofe Draft (electronic) 15 Sept 2010 DES Frances Mills, Leon Hill, Arlene Rofe Second draft 18 November 2010 DES (electronic) Peer reviews, Owen Nichols Second draft 18 November 2010 BGS (electronic) Frances Mills, Leon Hill, Arlene Rofe Final (electronic) 20 December 2010 DES ii Influences of hypersaline tailings on wildlife cyanide toxicosis: Granny Smith Gold Mine Preface This preface is to provide peer reviewers with the context and ramifications of this report in terms of the International Cyanide Management Code (Code) and Code compliance at Barrick Granny Smith Gold Mine (BGS). Three issues are discussed in this preface: the relevance of recommendations derived from this work; the necessity of collecting site-specific data to test hypotheses; and the site data used in this study. The effects of cyanide on fauna in tailings storage facilities (TSFs) are addressed primarily in Standard of Practice 4.4 of the Code. Code objectives, guidance on meeting the Code and auditing requirements are provided in additional documents [1-3]. A series of newsletters are also produced to inform the cyanide industry of new developments and provide clarification [4-7]. Recommendations The Code stipulates that cyanide will generally not kill wildlife at a concentration of less than 50 mg/L WAD cyanide [1]. The Code provides a process for mining operations to prove and demonstrate compliance in excess of this numerical guideline. This peer-reviewed process involves collecting and analysing site- specific empirical data to establish a causal relationship between identified protective mechanisms and the lack of wildlife deaths (p. 33 [2]). This process of hypothesis development and subsequent findings and recommendations follows the Code compliance process at Sunrise Dam, Kanowna Belle and St Ives gold mines. If any hypothesis describing a protective mechanism to an otherwise toxic solution is accepted then this is developed as a theory in the discussion of this report. Recommendations provided are to address limitations of the theory or dataset completeness and identify requirements for compliance with the Code. If accepted, the recommendations are binding and conditional for Code compliance. While these necessary practices may be termed “recommendations,” they are actually requirements for the operation’s compliance with this Standard of Practice. Since the operation must implement the recommendations and their implementation will be evaluated by Code auditors during the certification process, they should be drafted so that, to the extent practical, they are clear and unambiguous in presentation, specific and quantifiable. The operation must be able to demonstrate that the recommendations have been implemented in order to maintain compliance with this Standard of Practice (p. 33 [2]). Hypotheses testing The BGS Interim Report stated that to test the hypotheses proposed (and accepted at other mine sites following M398 and other work) the following conditions are required: • wildlife is present and interacts with cyanide-bearing habitats; • WAD cyanide at spigot discharge exceeds 50 mg/L; and • tailings slurry and solution exceeds 50 000 TDS mg/L. Causation was established with site-specific empirical data at the other hypersaline sites as the three conditions were continuously met. The WAD cyanide discharge concentration at BGS is variable, at times greater and less than 50 mg/L. This is expected to continue. The BGS Interim Report did not iii Influences of hypersaline tailings on wildlife cyanide toxicosis: Granny Smith Gold Mine include data collected while the system was hypersaline and spigot discharge was greater than 50 mg/L. Consequently the hypotheses were not tested with site-specific data. Subsequently, spigot discharge has been above 50 mg/L and the system is hypersaline, and data collected under these conditions is included in this report. It has not been recommended and would not be compliant with the Code to deliberately increase the cyanide dosage rate to further test the hypotheses. Standard of Practice 4.2 states: Introduce management and operating systems to minimise cyanide use, thereby limiting concentrations of cyanide in mill tailings (p. 3 [1]). The Implementation Guidance document goes on to state: Limiting cyanide use to the greatest extent practicable has environmental and economic benefits because reducing the concentration of cyanide lowers the risk of potential seepage and harmful exposures to wildlife, and minimising the amount of cyanide that must be transported to the site lowers the potential of transport-related releases (p. 10 [8]). And the Auditor’s Guidance document states: Standard of Practice 4.2 applies solely to milling operations, the intent being to limit the use of cyanide to that optimal for economic recovery of gold so that the waste tailings material has as low a cyanide concentration as practical (p. 28 [2]). This predicament produces the ironic and counter-intuitive position that to meet Code compliance (by hypothesis testing with empirical data only) the operation must discharge above 50 mg/L WAD cyanide concentration during all seasons and under all conditions. This is currently not necessary to meet process gold- recovery targets. A process is not articulated in the Code where a site discharges WAD cyanide concentrations above and below 50 mg/L (with protective mechanisms) and gains compliance yet one exists for sites that solely discharge over 50 mg/L (with protective mechanisms). To approach this issue this report provides site-specific data where WAD cyanide discharge concentrations are greater than 50 mg/L, however this report addresses causation and predicts risks while not continuously necessitating this requirement. This process is consistent with Standard of Practice 4.2 and does not necessitate or force the site to discharge above 50 mg/L WAD cyanide and hence continues to encourage a reduction in cyanide usage and meet the objectives of the Code. Dataset Wildlife cyanide toxicosis risk has been studied in a continuous and consistent manner at BGS since 2006, as part of the Sustainable Minerals Institute (SMI) (formerly Australian Centre for Mine and Environment Research (ACMER) P58), the Mining and Energy Research Institute of Western Australia (MERIWA) project M398 [9] and this work. Data from all studies is considered and incorporated in this report. The data collection methodology has been improved since M398 and aims for continuous improvement. iv Influences of hypersaline tailings on wildlife cyanide toxicosis: Granny Smith Gold Mine Executive Barrick Granny Smith Gold Mine (BGS) was one of the international mining operations involved in a study in 2006 under the auspices of the then Australian summary Centre for Mine Environment Research (ACMER) to investigate wildlife cyanide toxicosis risks associated with gold mine waste solutions. Subsequently, BGS was one of three mining operations that undertook a study of the effects of hypersalinity (greater than 50 000 mg/L total dissolved solids (TDS)) as a protective mechanism under the auspices of the Minerals and Energy Research Institute of Western Australia (MERIWA) as project 398 (M398). A salinity of 50 000 TDS is protective as wildlife cannot drink such saline water and avoids its ingestion during foraging activities. This current study builds upon and is a continuation of these previous studies. The M398 study was previously peer reviewed under the processes provided in the International Cyanide Management Code (Code) resulting in two sites (Kanowna Belle (BKB) and St Ives (GSI) gold mines) gaining full compliance due to acceptance of the hypothesised protective mechanisms. At the time BGS was documented as saline (14 000 to 21 000 mg/L TDS). A residual (theoretical) risk was therefore identified, even though no deaths were recorded during that study, as some wildlife species have been reported in the literature as able to drink solutions of up to 47 000 mg/L TDS (see Appendix 1). BGS continued to monitor the tailings storage facility (TSF) as stipulated in the recommendations of the M398 study. To address the identified theoretical